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Subject: Re: [SG10] New draft of SD-6
From: Ed Smith-Rowland (3dw4rd_at_[hidden])
Date: 2014-09-28 19:17:00


On 08/14/2014 07:37 PM, Nelson, Clark wrote:
> I have made a few minor revisions since N4030.
>
> The redlining in the document is relative to the published SD-6; I think
> that's the way we'll want to publish it. But here is what I've changed
> recently:
>
> In response to Ed Smith-Rowland's question about <optional> vs.
> <experimental/optional> I updated the __has_include example. Of course it's
> just an example, but I think it's more helpful now than it was.
>
> In response to Walter's question about the "policy" for the C++14 table, I
> minimally tweaked the text. :-)
>
> In response to Richard's question/complaint, I deleted "has" from the macro
> names for new features added by LWG issues.
>
> There are sentences in the rationale section about features removed from
> C++14 to a TS; I have changed them from editorial notes to plain old text.
> (I don't know what's going to happen with the array extension TS, but it is
> still an official project with an official number; hopefully something will
> come of it.)
>
>
> This still needs work in three areas:
>
> 1. We need introductory text and rationale for __has_cpp_attribute.
> (Richard?)
>
> 2. We need to approve what we want to do about the LWG issues that Alisdair
> brought up.
>
> 3. We need to make final determinations about shared_mutex.
>
> --
> Clark Nelson Vice chair, PL22.16 (ANSI C++ standard committee)
> Intel Corporation Chair, SG10 (C++ SG for feature-testing)
> clark.nelson_at_[hidden] Chair, CPLEX (C SG for parallel language extensions)
>
>
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I apologize for sending this so late but I thought I had lost some notes
regarding C++98 and C++11.
I collected some thoughts on "finishing" these areas if that is desired.

Here are some macros to finish-out C++11:

C++11
-----
N2439 __cpp_reference_qualifiers 200710 This has library usage
N2756 __cpp_nsdmi 200809 Hate to spell this out :-(
     __cpp_aggregate_default_initializers Or this, borrowed from
CMake?
N1986 __cpp_delegating_constructors 200604 Users can migrate
from initializer functions
N2540 __cpp_inheriting_constructors 200802 Ditto
N2930 __cpp_range_based_for_loops 200907
N2672 __cpp_initializer_lists 200806

Some popular C++ compilers still don't support all these.
It doeas add a few more macros but it finishes C++11.
Other compilers may emerge that need to "work their way up" through
these features.
I could go either way on this - I know some don't want to clutter up
compilers with lots of macros.

C++98
-----
     __cpp_exceptions 199711L

     __cpp_run_time_type_id 199711L

Rationale for __cpp_exceptions and __cpp_run_time_type_id:
Several compilers exist that allow the user to turn these features off
with a macro or a compiler switch.
Providing these macros enhance portability of such code that uses macros
to change code depending on availability of these features.

I just used the date standard when these were added to C++98 rather than
try to dig up old papers.



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